By the time the crowds broke up by late evening, about 100 people were arrested and 16 minor injuries were reported. That amounted to a victory for the pro-Western government, which arrested Mladic on Thursday, risking the wrath of the nationalist old guard in a country with a history of much larger and more-virulent protests.

Rioters overturned garbage containers, broke traffic lights and set off firecrackers as they rampaged through downtown. Cordons of riot police blocked their advances, and skirmishes took place in several locations in the center of the capital.

Doctors said six police officers were among the 16 people brought to a hospital with minor injuries. Police remained on the streets as the crowds broke up.

The clashes began after a rally that drew at least 7,000 demonstrators, many singing nationalist songs and carrying banners honoring Mladic, the former Bosnian Serb military commander. Some chanted right-wing slogans and a few gave Nazi salutes.

Supporters of the extreme nationalist Serbian Radical Party were bused in to attend the rally. Right-wing extremists and hooligan groups also urged followers to appear in large numbers, creating the biggest test of Serbian sentiment and the government's resolve since Mladic's arrest.

The demonstrators, who consider Mladic a hero, said Serbia should not hand him over to the U.N. war crimes court in The Hague, Netherlands.

"Cooperation with The Hague tribunal represents treason," Radical Party official Lidija Vukicevic told the crowd. "This is a protest against the shameful arrest of the Serbian hero."

Nationalists are furious that the Serbian government apprehended Mladic after nearly 16 years on the run. The 69-year-old former general was caught at a relative's home in a northern Serbian village.

The U.N. tribunal charged Mladic with genocide in 1995, accusing him of orchestrating the massacre of 8,000 Muslims in Srebrenica and other war crimes in Bosnia's 1992-95 war. Mladic's arrest is considered critical to Serbia's efforts to join the European Union and to reconciliation in the region after the ethnic wars of the 1990s.